Originally found in New Mexico, TCD affects many types of walnut trees to varying degrees but is lethal to black walnuts in the western United States. In the eastern United States, TCD has been detected in Tennessee, Virginia, North Carolina, Maryland, Pennsylvania and Ohio.

According to State Entomologist Phil Marshall, TCD has not been detected from a black walnut tree in the state of Indiana. Furthermore, Marshall doesn't expect widespread mortality from TCD anytime in Indiana in the near future.

Even in Eastern states where TCD has been detected, widespread die-offs haven't happened.

"If you are approached to sell your black walnut trees now because the 'walnut disease' (TCD) is coming, you should contact your consulting forester or district forester for advice," Marshall said. "Follow your current management plan and do not sell the walnut just because of TCD."

Marshall has received reports from consulting foresters in northeast Indiana that some of their clients have sold walnut trees when they did not need to.

TCD is caused by a fungus, Geosmithia morbida, that is transported by the walnut twig beetle.

The beetles bore into walnut branches, feeding on the tree's tissues and depositing the fungus that creates a canker, or dead area, under the bark. Multiple feedings cause the formation of thousands of cankers under the bark and destroy the tree's ability to transport water and nutrients. Gradually the tree dies.

While TCD hasn't been detected in Indiana, components of the disease have been. In 2014, the fungus was found on a weevil collected from a walnut tree in Yellowwood State Forest walnut plantation. None of the trees in the plantation contracted the disease. In 2015, walnut twig beetle was detected in baited traps at a Franklin County sawmill near the Ohio border. But the beetle hasn't been found in standing trees in Indiana.

The DNR is on the lookout for thousand cankers disease and the walnut twig beetle in Indiana. In 2015, the agency visually inspected 1,431 walnut trees in 10 communities across the state. It also set 249 baited beetle traps.

Black walnut is the most valuable tree in Indiana. There are an estimated 31.5 million walnut trees in Indiana. Approximately 17.7 million board feet of black walnut is harvested annually with a value of $21.4 million.